My mother never bothered to explain periods to me. Even though she was 9 when hers started.

Despite us not having a great relationship until well into adulthood, I am eternally grateful to my sister for giving me the talk. She's 5 years older than me and she started when she was 10. When I was 8 or 9 I remember her sitting me down and explaining periods to me. I also remember her explaining about certain body hair. She was so disgusted and ashamed when hers started growing that she would steal mum's razor and caused all sorts of problems for herself. (You'd think after that our mum would have thought that maybe she should explain some things to her younger daughter but no)

Anyway, I was the late starter in our family (considering I have PCOS, not surprising) and started when I was 11. Luckily that was after school had covered it so I would have had some idea of what was happening but not as well as my sister explained.

My niece is 10 and is probably going to start soon. She's going to be fine though (well apart from the fact she's probably doomed to have gynae issues at some point, everybody in our family does), she's known about periods since she was a toddler.